The sale by ING North America Insurance Corp. of its nearly 1 million-square-foot Minneapolis office complex is partly “an asset efficiency play,” according to a party to the deal, and partly a response to a tightening office market in downtown Minneapolis.The campus, purchased by National Office Partners LP, an investment partnership between Hines and the California Public Employees’ Retirement System, consists of three office buildings built over a 20-year span. ING’s Minneapolis headquarters, 20 Washington Avenue, is a six-story, 148,000-square-foot office building designed by Minoru Yamasaki & Associates and completed in 1964. It’s fully occupied by ING. The largest building, at 22 stories and 481,604 square feet, is 100 Washington Avenue, also designed by Minoru Yamasaki & Associates. Built in the 1980s, it’s 82 percent leased to tenants including ING, Wells Fargo Bank N.A., Northwestern Mutual, Special Olympics Minnesota and Lockridge Grindal Nauen PLLP.The third building is 111 Washington Avenue, a 15-story, 359,237-square-foot office completed in 1987 and currently 48 percent leased to tenants including the FBI, Wells Fargo Bank N.A. and ING. A seven-level, 1,000-space parking ramp at 25 North First Street rounds out the complex. A source knowledgeable about the transaction pegged its value at approximately $120 million. Hines vice president John McDermott explained to CPN that although ING will be consolidating its occupancy almost entirely in the 20 Washington and 100 Washington buildings, and the 111 Washington building will be left “pretty much vacant,” there won’t be any net reduction in ING’s square footage. Rather, he said, part of the transaction’s value will come from the fact that “We’re getting big, large contiguous spaces to rent.” The office market in downtown Minneapolis, he said, is particularly tight for spaces of 50,000 to 100,000 square feet and larger. McDermott told CPN that although the office vacancy rate in downtown Minneapolis is trending down, “Rents aren’t high enough to support new construction yet.” He estimates that the purchase price for the ING complex is one-third below the cost of new construction.